1. Field of the Invention
This invention relates generally to a rear and side object detection system for a vehicle and, more particularly, to a rear and side object detection system for a vehicle that incorporates an antenna configuration that defines overlapping antenna fields around the vehicle where the antenna fields combine to give an accurate detection of obstacles within a desirable obstacle detection region.
2. Discussion of the Related Art
For current vehicle transportation, there is a significant number of incidences involving vehicle collisions with obstacles, such as other vehicles, when the vehicle is changing travel lanes or merging, and when the vehicle is operating in reverse. The main reason why the lane change/merge and reverse operation incidences occur is because the vehicle operator is unaware of the obstacles in the vehicle's intended path. Many factors relate to why the vehicle operator would be unaware of the obstacles. These factors include operator fatigue, carelessness, distraction by other conditions, and blocked vision. This suggests that many of these crash incidences can be avoided by vehicle based countermeasures that inform the vehicle operator of the presence of an obstacle when the vehicle operator initiates a lane change or back-up maneuver.
Currently, progress is being made in the applicable technological fields to achieve an effective rear and side object detection system that informs a vehicle operator of an impending collision with many types of objects that may be present within the vehicle's intended path. In most practical detection systems of this type, radar technology is utilized. Particularly, a radio wave signal at a desirable frequency is emitted from the detection system to define a desirable sensing zone around the vehicle, and reflected signature signals from objects within the zone are received by the system to be analyzed. Positional information from the signature signals and the relative timing between the transmitted radio wave signal and the reflected signature signals provide an indication of the location, distance and speed of the objects. A background discussion of typical obstacle detection systems known in the art can be found in U.S. Pat. Nos. 5,087,918; 5,008,678; 4,349,823 and 3,697,985.
It does not appear that the current technology has reached a level that would make radar detection systems feasible in a wide variety of mass produced vehicles. This is because of a number of necessary design criteria required for a practical detection system. Generally, the detection system must be low cost and readily adaptable to various types of vehicles with respect to consumer demands and industry standards. More importantly, the detection system must be reliable in that the system must give a warning indication of an obstacle of the type that may cause a collision for a high percentage of the times, and not provide a warning or nuisance signal for those objects that do not provide a chance of collision.
To achieve reliable object detection, the detection system must accurately define sensing zones around the vehicle. The requirement for highly defined sensing zones can be realized by understanding the following situation. The detection system must emit a signal of a sufficient power that will cause a small child to generate a significant reflection signature signal if the child is behind the vehicle in a potentially hazardous position. However, it would be undesirable to provide a warning signal of a metal obstacle that was significantly distanced from the back of the vehicle where it would not be a potential collision hazard. Because the metal object would provide a much greater reflection signature than the child when at the same distance for the same power level, the design of the system must define the sensing zones to separate these two events to be practical.
To detect objects in the proximity of a vehicle to be effective against lane change/merge and back-up collisions, the detector system must be able to cover specific areas to the left, right and back of the vehicle. In order to create this necessary coverage without sacrificing aesthetics and to avoid packaging problems, a multiple detector system configuration is necessary. However, it becomes important from a design standpoint to limit the number of power sources and antenna in the system because of space and cost constraints.
What is needed is a rear and side obstacle detection system that accurately defines effective sensing areas around a vehicle so as to give a high probability of detection when a potential collision causing obstacle is within the sensing areas, and prevent the system from indicating an obstacle is present when one is not present in the sensing areas. It is therefore an object of the present invention to provide such a rear and side object detection system.